Turkish Prime Minister Binali Yildirim’s chief adviser was detained on Saturday over suspected links to the movement of US-based Muslim cleric Fethullah Gulen blamed for last year’s failed coup, state media reported. Birol Erdem, a former senior justice ministry official, was taken into custody in Ankara along with his wife Gulumser Erdem, Anadolu news agency said. He was accused of being a member of the movement led by Gulen, the agency reported, quoting sources from the office of the Ankara chief public prosecutor.

The Turkish government claims Gulen ordered the July 15 attempt to oust President Recep Tayyip Erdogan from power. Gulen, who has lived in self-imposed exile in Pennsylvania since 1999, denies the charges. Erdem is one of the most senior bureaucrats to be suspected of Gulen links. Others who have been detained come from the military including Erdogan’s aide-de-camp Colonel Ali Yazici.

Erdem was called to testify as a witness last year fin an investigation into followers of Gulen’s movement after several suspected members named him in their testimonies, Hurriyet daily reported. Turkish authorities have arrested over 50,000 people including judges, prosecutors, police officers and members of the armed forces, accusing them of having connections with the Gulen movement, justice ministry officials told Anadolu last week. Meanwhile, over 100,000 working in the public sector including doctors, civil servants and academics have been suspended or sacked over alleged links to the movement.